The field of art to which this invention pertains includes inlet-exhaust construction incorporating a muffler on pneumatic hand tools.
The majority of commercially available pneumatic hand tools include a muffler of sorts. These mufflers are usually used in tools having an exhaust extension or the like whereby the muffler can be accommodated, for instance, those shown in U.S. Pat. Nos. 3,880,245 and 3,299,781. Another approach to the problem includes U.S. Pat. No. 3,823,795, where the exhaust air is directed forwardly, and space is provided in the top of the handle, above the hand grip area, for muffling.
In the first example, extensions on the exhaust passage are bulky and expensive and up until the present invention, utilized separate passages throughout the length of the handle for inlet and for exhaust. In the second example, in addition to the space requirement between the operators hand hold and the motor, the forwardly directed air is undesirable, providing an opportunity to mark a workpiece with the lubricant commonly included in the air supply to pneumatic tools.